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Two Critical Water Pollutants Affecting Human Health – Mercury and PCBs

Two Critical Water Pollutants Affecting Human Health – Mercury and PCBs. 1. Heavy Metals. Naturally Occurring (in rock) Also released by human activities Mercury (Hg), Lead ( Pb ), Cadmium ( Cd ), Copper (Cu), Arsenic (As) + others All are neurotoxins

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Two Critical Water Pollutants Affecting Human Health – Mercury and PCBs

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  1. Two Critical Water Pollutants Affecting Human Health – Mercury and PCBs

  2. 1. Heavy Metals • Naturally Occurring (in rock) • Also released by human activities • Mercury (Hg), Lead (Pb), Cadmium (Cd), Copper (Cu), Arsenic (As) + others • All are neurotoxins • All can bioaccumulate (build up in the tissues, not excreted) • All can biomagnify (concentration increases “up the foodchain”)

  3. Mercury • Very rare in the Earth’s crust • Only metal that is liquid at room temp. • Uses: thermometers, preservative in vaccines, dental fillings, mercury-vapour lamps……

  4. Example: Mercury (Hg) • Minimata, Japan • Mercury from a chemical plant released into the bay 1930s-1960s • About 2000 deaths and 10,000 ill • 1956 – “Minimata disease”…..difficulty walking and speaking, convulsions • Cause was identified by 1958 – mercury in fish

  5. Grassy Narrows, Ontario

  6. Grassy Narrows - Ontario • Late 1960s • First Nations people experience symptoms similar to Minimata (blurred vision, speech and hearing, tremors…) • Japanese doctors called in to help • Source: paper bleaching factory (Dryden Pulp and Paper Company) • Over 9000 kg of mercury was dumped into the Wabigoon-English River system before ordered to stop in 1970

  7. http://archives.cbc.ca/environment/pollution/topics/1178/ • http://www.cbc.ca/thenational/blog/2010/04/grassy-narrows-marred-by-mercury.html • http://www.cbc.ca/video/#/Shows/The_National/Environment/1290117620/ID=1461698083

  8. 2. PCBs • Polychlorinated Biphenyls • Used but never produced in Canada • Not naturally occurring – manufactured in U.S. 1929-1977 • Versatile chemical – many uses • Resistant to acids and bases • Resistant to heat

  9. Used as an insulating material in electric equipment, such as transformers and also in heat transfer fluids and in lubricants. • used in wide range of products such as plasticizers, surface coatings, inks, adhesives, flame-retardants, paints …

  10. Slow to break down – 2,000,000 tons produced – 10% remain in the natural environment

  11. Disposal – (e.g. decommissioned transformers) – must go to an approved storage site • 23 sites in Ontario where they remain “in storage” • 2011 – federal regulation is that by the end of this year, they are to be disposed of (probably by incineration) • Health effects – cancer, liver damage, nervous/immune system damage

  12. PCB storage site – South Etobicoke (Toronto)……notice in the background how close residential neighbourhoods are!

  13. PCBs • Can bioaccumulate – can be found in Ontario lake fish • refer to The Guide to Eating Ontario Sport Fish for consumption advice.

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